Scavenger Effects

Fossils only rarely intact (i.e. complete and articulated) and can be a collection of all kinds of odd bones that you would not necessarily expect to find together. Many pieces will be retained in close association (e.g. the vertebral column) but others will drift or be destroyed in quite unpredictable ways. I’ll be writing more on this subject later, just wanted to put up this nice picture that demonstrates the point really quite well.

I took this in Mexico and it shows the remains of a donkey that has been thoroughly picked over by coyotes and feral dogs as well as huge numbers of vultures (and possibly but unlikely the odd wolf or bear which are in the area thought his was way too close to a town for them to be likely and tracks would probably have been visible).  Despite the work that has clearly gone into picking the animal clean of meat (it’s literally just skin and bone) the majority of the skeleton is basically there and intact and aside from being a bit folded up, is also still articulated.

Even so the pelvis appears to have gone as well as at least one leg, even though the rest is fine. There was no sign of them, so any palaeontologist coming in a few million years from now will find what we sometimes do with our own discoveries – an otherwise intact skeleton with a few bits mysteriously missing from the middle.

The place where I found this was the back of a dump and was clearly a place where animal corpses were left for the local wildlife to pick over but it made of a fascinating (if often stinking) lesson in taphonomy and how things decay. Here are a couple more photos showing different aspects of scavenging and skeletal break up. First off there is a whole swathe of bones that have been separated out and scattered over a small area. Apart form the odd pair of bones still together, pretty much everything here is mixed up from several animals, and it’s hard to work out how many there likely were originally. While of course they animals were dead when they were brought here, one can easily imagine a small herd of animals dying at a waterhole and this being the result of the local predators and scavengers picking over them, before a flash flood or sand storm buries them and leaves a bone bed in the making.

Last we have this one, a partial skeleton where the ribs and vertebral column is almost completely intact. The head and legs and tail has gone, but the rest is there and undisturbed. Ribs are normally one of the first things to go, and of course vertebrae often separate, so this is an interesting example.

That’s it for now. There is (as often promised on these pages) more to come on this subject, but this should keep the ghoulishly interested in rotting donkeys going for a while.